gams:different_variable_types_within_one_definition

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gams:different_variable_types_within_one_definition [2020/05/26 12:14] Lutz Westermann |
gams:different_variable_types_within_one_definition [2020/05/26 12:19] (current) Lutz Westermann link to docu; remove reference to very old gams version |
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- | Starting with Distribution 22.1 this can be achieved using the priority attribute. The priority attribute of a discrete variable can be used to relax a specific variable instance. The priority attribute ''.prior'' establishes in what order variables are to be fixed to integral values while searching for a solution. Variables with a specific ''.prior'' value will remain relaxed until all variables with a lower ''.prio''r values have been fixed. Setting the .prior value to +inf will relax this variable permanently. This relaxation is done independent of the model attribute ''.prioropt''. | + | This can be achieved using the [[https://www.gams.com/latest/docs/UG_Variables.html#UG_Variables_VariableAttributes|priority attribute]]. The priority attribute of a discrete variable can be used to relax a specific variable instance. The priority attribute ''.prior'' establishes in what order variables are to be fixed to integral values while searching for a solution. Variables with a specific ''.prior'' value will remain relaxed until all variables with a lower ''.prio'' values have been fixed. **Setting the .prior value to +inf will relax this variable permanently.** This relaxation is done independent of the model attribute ''.prioropt''. |

- | This feature is useful in solving difficult discrete models. The Model Library model "Linear Recursive Sequence Optimization Model" (''lrs.gms'') illustrates the use of this feature that specifies that only the first n variables of k are binary, whereas the remaining ones are fractional. Find below a simple example: | + | This feature is useful in solving difficult discrete models. The Model Library model "Linear Recursive Sequence Optimization Model" ([[https://www.gams.com/latest/gamslib_ml/libhtml/gamslib_lrs.html|lrs.gms]]) illustrates the use of this feature that specifies that only the first n variables of k are binary, whereas the remaining ones are fractional. Find below a simple example: |

<code> | <code> | ||

Set a 'all variables' /a1*a5/ | Set a 'all variables' /a1*a5/ |

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